US ambassador to the UN says US could announce as early as Monday new sanctions on Moscow for support of Syria's Assad.

Russian Deputy Foreign Minister Sergei Ryabkov has said Moscow will not delay its response to new US sanctions, according to Russian state news agency RIA.

Ryabkov's comments on Monday came in response to remarks made by Nikki Haley, the US ambassador to the UN, who said on Sunday that Washington will impose new economic sanctions on Russia for their support of Syrian President Bashar al-Assad.

Ryabkov said that Russia's lower house of parliament is considering legislation that would give the Kremlin the power to restrict US imports, RIA reported.

The deputy foreign minister also said Russian politicians were discussing US "abuse" of the dollar's status as the international currency, RIA quoted Ryabkov as saying.

Syrian government forces are suspected of using chemical weapons on rebel-held Douma on April 7 - an allegation that Syria's Assad denies.

The US, France and the UK responded to the suspected attack by launching missiles on Saturday that they said targeted Syrian chemical weapons production facilities. Russian President Vladimir Putin denounced the US-led strikes as "an act of aggression" that will only worsen the humanitarian crisis in Syria.

Haley told US media that sanctions could come as early as Monday.

"You will see that Russian sanctions will be coming down," Haley said

The US has already sanctioned Russia over its annexation of Crimea and role in the Ukraine conflict, as well as its alleged meddling in the 2016 presidential election.

The administration of US President Donald Trump is mired in controversies surrounding the Department of Justice's investigation into alleged Russian meddling and possible collusion between the Trump campaign and the Kremlin.

On Friday, it came out in court that Trump's longtime lawyer Michael Cohen has been under criminal investigation for months.

Former FBI Director James Comey, who was fired by Trump, also compared the US leader to a mafia boss and said he was "morally unfit" to be president, stoking controversies.